Patient support systems with rotary actuators comprising rotation limiting devices

Abstract

A patient support system comprises a patient support apparatus for patients. The patient support apparatus comprises a base and a patient support surface supported by the base. The patient support apparatus also comprises movable members that are movable between at least a first position and a second position. One or more rotary actuators with rotation limiting devices are coupled to each movable member. The actuator with the rotation limiting device permits drive torque to move the movable member in a desired position between the first and second positions and restricts back drive torque from moving the movable member.

The invention claimed is: 
     
       1. A patient support apparatus comprising:
 a patient support surface; 
 a first member and a movable member, said movable member movable relative to said first member; and 
 an actuator comprising:
 a gear assembly having an input element, an output element connected to said movable member, and a gear arrangement operable between said input element and said output element; 
 a motor configured to apply drive torque to said input element to rotate said output element through said gear arrangement; and 
 a rotation limiting device coupled to said gear assembly to permit movement of said movable member relative to said first member through application of said drive torque from said input element to said output element and prevent back drive torque applied to said output element from moving said movable member in at least one direction relative to said first member; 
 wherein said rotation limiting device comprises a braking surface and a braking element, said braking element operably coupled to said input element and said output element for concurrent movement with said input element and said output element, with said braking element engageable with said braking surface to prevent back drive torque applied to said output element from moving said movable member relative to said first member. 
 
 
     
     
       2. The patient support apparatus of  claim 1 , wherein said rotation limiting device comprises a first brake plate, a second brake plate, and a roller clutch bearing disposed between said first brake plate and said second brake plate, and wherein at least one of the first brake plate and the second brake plate comprises the braking surface, and wherein the roller clutch bearing comprises the braking element. 
     
     
       3. The patient support apparatus of  claim 2 , wherein said roller clutch bearing comprises an outer race releasably coupled by friction force between said first brake plate and said second brake plate, and an inner race disposed within said outer race and coupled to said input element, with said inner race configured to rotate relative to said outer race in a first direction in response to said drive torque from said motor, and with said inner race configured to rotate with said outer race relative to said first and second brake plates in a second direction in response to said drive torque from said motor. 
     
     
       4. The patient support apparatus of  claim 1 , wherein said rotation limiting device comprises a housing and said braking element forms part of a braking assembly, with said braking element of said braking assembly comprising a first lock cam movably coupled to said housing, and said braking assembly comprising a second lock cam movably coupled to said housing. 
     
     
       5. The patient support apparatus of  claim 4 , wherein said rotation limiting device comprises an outer ring operably coupled to the housing, said outer ring comprising the braking surface, and wherein said first and second lock cams are configured to engage the braking surface of the outer ring. 
     
     
       6. The patient support apparatus of  claim 4 , wherein said first and second lock cams are independently movable relative to said housing between a first position in contact with said braking surface, a second position spaced from said braking surface and at least one intermediate position between said first and second positions. 
     
     
       7. The patient support apparatus of  claim 6 , wherein said housing is restricted from rotating in a first direction relative to said braking surface when said first lock cam is in said first position and said housing is restricted from rotating in a second direction relative to said braking surface when said second lock cam is in said first position. 
     
     
       8. The patient support apparatus of  claim 7 , wherein said housing is free to rotate in said first direction when said first lock cam is in said second position and said housing is free to rotate in said second direction when said second lock cam is in said second position. 
     
     
       9. The patient support apparatus of  claim 8 , wherein said rotation limiting device further comprises a no-back input shaft rotatable relative to said braking surface and said housing in response to said drive torque from said motor. 
     
     
       10. The patient support apparatus of  claim 9 , wherein said rotation limiting device further comprises a no-back gear arrangement between said no-back input shaft and said first and second lock cams to independently move said first and second lock cams between said first and second positions in response to rotation of said no-back input shaft. 
     
     
       11. The patient support apparatus of  claim 10 , wherein said rotation limiting device comprises a drive dog fixed to said no-back input shaft and said housing comprises at least one protrusion, wherein said drive dog is configured to abut said protrusion when said no-back input shaft is rotated to interconnect rotation of said no-back input shaft to said housing so that said housing rotates with rotation of said no-back input shaft. 
     
     
       12. The patient support apparatus of  claim 11 , wherein said protrusion is spaced from said drive dog such that said no-back input shaft rotates one of said first and second lock cams to said second position before said drive dog abuts said protrusion. 
     
     
       13. The patient support apparatus of  claim 1 , wherein said gear assembly comprises a first planetary gear train and a second planetary gear train operably connected in sequence with said first planetary gear train. 
     
     
       14. The patient support apparatus of  claim 13 , wherein said first planetary gear train comprises a first planetary gear train input gear rotatable about a center axis and configured to receive said drive torque from said motor, a first planetary gear train output member rotatable about said center axis and coupled to said rotation limiting device, and a first planetary gear train gear arrangement operable between said first planetary gear train input gear and said first planetary gear train output member with said first planetary gear train gear arrangement configured to transmit drive torque available at said first planetary gear train input gear to said first planetary gear train output member and said rotation limiting device. 
     
     
       15. The patient support apparatus of  claim 14 , wherein said second planetary gear train comprises a second planetary gear train input gear coupled to said rotation limiting device, a second planetary gear train output member rotatable about said center axis, and a second planetary gear train gear arrangement operable between said second planetary gear train input gear and said second planetary gear train output member. 
     
     
       16. The patient support apparatus of  claim 15 , wherein said input element comprises said first planetary gear train input gear and said output element comprises said second planetary gear train output member. 
     
     
       17. The patient support apparatus of  claim 16 , wherein said motor is configured to rotate said first planetary gear train input gear about said center axis, which rotates said first planetary gear train output member about said center axis, which rotates said rotation limiting device about said center axis, which rotates said second planetary gear train input gear about said center axis, which rotates said second output member about said center axis, which moves said movable member relative to said first member. 
     
     
       18. The patient support apparatus of  claim 1 , wherein said movable member comprises one or more of a lift member, a patient support deck member, a bed length extension member, a bed width extension member, a wheel, a side rail, a footboard, or a headboard. 
     
     
       19. The patient support apparatus of  claim 1 , comprising a patient support deck having a base section and a movable section movable relative to said base section, wherein said actuator is mounted to said base section and said movable section comprises said movable member. 
     
     
       20. The patient support apparatus of  claim 1 , comprising a patient support deck having a fowler section and a seat section, wherein said actuator is mounted to said seat section and said fowler section comprises said movable member. 
     
     
       21. The patient support apparatus of  claim 1 , comprising a patient support deck having a foot section and a seat section, wherein said actuator is mounted to said seat section and said foot section comprises said movable member. 
     
     
       22. The patient support apparatus of  claim 1 , comprising a support frame, a base, a first lift member, and a second lift member movable relative to said first lift member to lift and lower said support frame relative to said base, wherein said actuator is mounted to one of said base, said support frame, said first lift member, and said second lift member.